Slide-gate pouring appliances for ladles and similar devices have been commonly used for about two decades now. They were however designed far earlier, at the beginning of the last century, and the long delay before they were applied must be blamed on the fact that to enable them to operate properly, refractory bricks with high mechanical, thermal and chemical properties are required.
These properties have become available only relatively recently, and since then slide-gate pouring appliances have continued to become increasingly widespread.
First of all they were applied to smaller gates and then, gradually, to larger ones.
Ever since slide-gate pouring appliances were first introduced, attempts have been made to find solutions allowing replacement of at least some of the firebricks from outside the ladle, thus simplifying and speeding up maintenance operations.
It is well-known that the basic refractory elements of a slide-gate shut-off device consist of two holed plates of which one fixed and one sliding, of a sleeve below the sliding refractory plate known as the external pouring appliance and a sleeve above the fixed refractory plate known as the internal pouring appliance.
The internal pouring appliance is not directly surrounded by the refractory lining of the ladle, but isolated from it by means of a larger sleeve, called the pouring-applicance holder and which, unlike the internal pouring appliance has to be fitted and replaced from inside the ladle.
This pouring-appliance holder is also an integral part of the slide-gate pouring appliance.
In designing the refractory parts of slide-gate shutoff devices, it is of the utmost importance to achieve uniform wear of the parts so as to space maintenance activities efficiently.
It is however not easy to achieve similar rates of wear for elements working in different ways and therefore in the past it was found preferable to simplify the typology of the refractory elements forming the pouring appliance so at least the number of parts to be stocked was reduced.
This criterion is used in nearly all cases, but the different wear rates of the various components are magnified by the increased dimensions of the shut-off devices, and it is therefore necessary to choose between two alternatives:
(a) To reduce the number of stoppages for maintenance activities by replacing all the parts at the same time, even if some are only partly worn;
(b) To increase the number of stoppages for maintenance activities, replacing each time only those parts which have reached the maximum permissible limits of wear.
The first of these alternatives means a considerable waste of materials, and the second means interrupting the work cycle more frequently, reducing the exploitation of the production facilities.
The aim of this invention is to implement a large slide-gate shut-off device, the parts of which will wear out at the same rate.
In this way it will be possible to space maintenance activities further apart, without the wastages caused by early replacement of parts which are not yet fully worn out.
According to this invention, this aim has been fulfilled not only simply by increasing the dimensions (for example the thicknesses) of the parts which wear out more rapidly but also and above all by correctly configuring the various parts of the shut-off device.